Recently, electrophotographic image forming apparatuses used in the field of quick printing are being developed. In this situation, there is a need for image forming apparatuses having performance equivalent to that of printers conventionally used in the field of quick printing, in terms of high-speed, output, low-energy consumption, and high quality image formation. For the above purpose, efforts are being made to reduce energy consumption by, for example, reducing standby power consumption. In parallel with these efforts, it is contemplated to lower fixing temperature in a fixing step that consumes the highest amount of energy. In addition, to support high-speed printing, studies are being made to prevent an image supporting material such as a paper sheet from being wound around a fixing member, i.e., to improve post-fixing separability. Generally, to improve the post-fixing separability, it is known to introduce a thermoplastic elastomer such as a block copolymer into a binder resin making up a toner. For example, Patent Literature 1 discloses the introduction of a block copolymer having a specified storage elastic modulus. Patent Literature 2 discloses the introduction of an entropy elastic resin composed of polyisoprene and polystyrene.
To improve the low-temperature fixability of a toner, the meltability of a binder resin is improved. However, the higher the meltability, the lower the viscoelasticity of the binder resin. Such low viscoelasticity causes a reduction in separability from a fixing member in a fixing step, and a winding phenomenon occurs. Therefore, with the thermoplastic elastomers disclosed in Patent Literatures 1 and 2, the two objects, i.e., improvements in low-temperature fixability and post-fixing separability, cannot be achieved simultaneously because the toner does not have a structure having domains formed therein and therefore cannot exhibit sufficient effects. Even if the objects can be achieved, the degree of achievement is not sufficient.